Field of the Invention
The invention relates to a tunable laser and a tuning method using the same.
Description of the Related Art
A typical Distributed Bragg Reflector (DBR) tunable laser, as shown in FIG. 1, includes: a gain section, a phase section, and a grating section. The largest tuning range of the wavelength of the DBR tunable laser is approximately 22 nm. To enlarge the tuning range, Vernier effect can be adopted, as shown in FIGS. 2 and 3, in which, two different grating structures are utilized to generate two multi-peak comb-like reflection spectra with different wavelength spacings, and currents are injected into the two different grating structures. However, the fabrication of the grating structures requires both complex regrowth steps and high-resolution processing like electron-beam lithography, which increases the difficulty and the production cost in the fabrication of the laser.